1. Field of the Invention
The present invention relates to a disk device that drives a disk-shaped recording medium for rotation.
2. Description of Related Art
Hitherto disk devices have been widely put into use, which write or read data on and from a disk-shaped recording medium such as a CD (Compact Disc), DVD (Digital Versatile Disc) or HD (Hard Disk) while driving the medium for rotation. It is known that flapping of a disk-shaped recording medium, which is referred to as “flutters” occurs when the disk-shaped recording medium is rotated. Under the circumstance, configurations for reducing flutter during rotation of a disk-shaped recording medium are known (for example, see Reference 1: JPHei 11-232866A, the left column of p. 3 to the right column of p. 4, and Reference 2: JP2001-338482A, the right column of p. 2 to the right column of p. 3).
In a configuration disclosed in Reference 1, a gap between an outer circumference of a disk in a magnetic disk device and an inner wall of a shroud is reduced to a predetermined distance to eliminate any difference in air pressure between the top and bottom sides of the disk and to thereby reduce the amplitude of flutter. In a configuration disclosed in Reference 2, a gap between one surface of a disk and stationary walls of a base and a cover opposing the disk surface is kept at 1 mm or less to reduce flutter generated by a difference between the pressures of airflows generated when the disk is rotated. Further, in the configuration disclosed in Reference 2, a shroud member is provided on the cover in a region of the shroud opposing an actuator chamber in the vicinity of a magnetic head to form a labyrinth between the chamber and the shroud such that an airflow which has been circulated in the actuator chamber will not flow into the vicinity of the magnetic head. Vibration of the magnetic head is thus suppressed.
Increase in rotating speed of disk-shaped recording media is proceeding in order to reduce the time required to read or record data. As a result of the increase in the rotating speed, the generation of flutter has become significant. In particular, needs for recording data in higher densities have resulted in demand for reduction of flutter.